Lack of dietary effects on the timing of smoltification in Atlantic salmon

Six commercially available diets varying in lipid, protein, water, ash, and carbohydrate contents were fed to Atlantic salmon (Salmo salar) for 2 years to determine if diet affected smoltification. Each month, from March to September of the second year, sampled fish were exposed to 33‰ seawater for 24 h to determine smolt readiness, defined as the ability to maintain water and salt balance in a seawater challenge. Regardless of diet, Atlantic salmon were able to regulate plasma sodium and chloride ions (smoltify) only during early May. It is unlikely that hatchery managers could effectively use high‐energy diets to control the time of smoltification in Atlantic salmon.